Influence of firing temperature on correlation between thermal shock and mechanical impact resistance of refractory castables

Three refractory castables used in the aluminium industry were investigated to establish correlations, which can be applied in practice, among the relevant properties important for performance in service. To determine the influence of firing temperature on the correlations, samples were fired at 1200 and 1450°C followed by mechanical impact (at 900°C) and thermal shock tests (quenched from 950°C into water). The relevant properties were evaluated including modulus of rupture, elastic modulus, work of fracture, and thermal expansion coefficient. The results show that there is a positive correlation between thermal shock and the mechanical impact resistance as well as with the σ_o R_st parameter at 1200°C. Two other positive correlations were established at 1450°C, the first involving mechanical impact resistance, modulus of rupture, and σ_o R_st, and the second between thermal shock resistance and the R′′′′ and R_st parameters.